The present invention relates to a mounting arrangement for a heat alarm. More specifically, the present invention relates to a heat alarm that includes a magnetic mounting arrangement that allows the heat alarm to be mounted to a face surface of an electric panel cabinet and non-invasively monitor the temperature within the cabinet.
Electric panel cabinets typically house the main electric service panels or subpanels for the electric supply to a building. Electric panel cabinets typically contain many components that may overheat and start fires, such as feeder conductors, branch circuit conductors, circuit breakers, fuses, and bus bars. The overheating of one of these electrical components within the electric panel cabinet can be caused by many types of malfunctions, such as loose or corroded connections, power overloads, or other malfunctions in the components themselves. When one of the electric components malfunctions, the large amount of voltage and current flowing through the components causes heat buildup within the cabinet and ultimately can ignite a fire within the cabinet, which then creates a fire hazard.
Although smoke alarms are required to be in every residential or commercial building by the majority of local building codes, these smoke alarms often do not provide adequate protection against fires started in the electric panel cabinets. Specifically, smoke alarms are often not located near the electric panel cabinet, since the electric panel cabinet is typically located in a remote area of the building away from the normally occupied areas. Even if a smoke alarm is located near the electric panel cabinet, the smoke alarm typically reacts only after a fire has started and a sufficient amount of smoke has been produced. In an electric panel cabinet, an overheat condition may exist for hours or even days before smoke is present to trip a smoke alarm. Thus, an opportunity exists to activate an alarm before a fire starts by sensing an overheat condition occurring within the electric panel cabinet. Additionally, since many smoke alarms are connected to the building's electrical system, a fire started in the electric panel cabinet can cause a loss of electric power, which then disables the smoke alarm.
Altavela U.S. Pat. No. 5,461,367 teaches an electric panel heat alarm that responds to an overheat condition within an electric panel cabinet. The alarm disclosed in the '367 patent positions a heat sensor within the enclosed area defined by the cabinet and uses a battery power supply to activate an audible alarm when the temperature within the electric panel cabinet exceeds an upper temperature limit. While the alarm disclosed in the '367 patent operates to indicate an overheat condition in the electric panel cabinet, the alarm of the '367 patent suffers from several drawbacks. Specifically, the alarm of the '367 patent includes a metallic conduit nipple extending between the alarm enclosure and the electric panel cabinet through a knockout opening contained in the top wall of the electric panel cabinet. Thus, in order to use the alarm disclosed in the '367 patent, the electric panel cabinet must either include a knockout opening or have an opening formed in its top wall. Additionally, if the electric panel cabinet is positioned in a building in a manner that makes the top wall of the electric panel cabinet inaccessible, the alarm disclosed in the '367 patent cannot be used in the manner disclosed. Thus, the mounting arrangement of the alarm disclosed in the '367 patent provides limited mounting options when the electric panel cabinet is positioned in a tightly confined area.
Further, the alarm of the '367 patent positions the heat sensor within the interior of the cabinet. Accordingly, the heat sensor can only detect an overheat condition when heat is conducted to the location of the heat sensor by the static air within the interior of the cabinet. It has been found that the static air within the interior of the cabinet is a poor conductor of heat. This can result in a significant time lapse between initiation of an overheat condition and detection of the overheat condition by the heat sensor, especially when the heat sensor is in a remote location within the cabinet from the heat source.
It is therefore an object of the present invention to provide a heat alarm that responds to an overheat condition in an electric panel cabinet by activating an audible alarm. It is a further object of the invention to provide a heat alarm having a mounting arrangement that allows the heat alarm to be positioned in multiple locations on the electric panel cabinet, and which overcome the drawbacks involved in relying upon heat conduction by the static air condition within the cabinet interior. Yet another object of the invention is to provide a heat alarm in which the mounting arrangement provides a magnetic attachment to the electric panel cabinet, thereby eliminating the need for a knockout opening in the electric panel cabinet. It is a further object of the invention to provide a sensor mounting arrangement that provides the required bias force to hold a heat sensor in contact with the electric panel cabinet when the heat alarm is mounted to the electric panel cabinet.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.